Conventionally, a variety of tests are carried out against adhesive sheets for checking adhesive-strength, retention strength, tacking strength, or the like. Adhesive characteristic being one of such test items is represented by adhesive strength which is measured at the time of peeling off the adhesive sheet from a specific substrate at 180.degree. or 90.degree. of angle against the surface of the substrate adhered with the peeled portion of the adhesive sheet. For example, adhesive-strength at the time of peeling off the adhesive sheet from the adhered substrate at right angles denotes the strength of inhibiting the adhesive sheet from being peeled off from the surface of the adhered substrate in the vertical direction.
Based on JIS (Japan Industrial Standard), the adhesive-strength is calculated from load which is applied at the time of peeling off the adhesive sheet from the adhered substrate at a constant speed. However, since any of those conventional adhesive-strength measuring apparatuses securely fixes the substrate itself adhered with adhesive sheet onto the surface of the apparatus to hold the tip end of the adhesive sheet to be peeled off from the adhered substrate, the adhesive-strength measuring apparatus is provided with large dimensions and weight to result in the inconvenience for carrying it to a specific location.
Concretely, when measuring the adhesive strength at the time of peeling off the adhesive sheet from the substrate at right angles, since the peeling position shifts as the peeling operation goes on, either the substrate fixed part, or the mechanism of the apparatus which pulls the adhesive sheet from the substrate should precisely and delicately be moved to prevent the peeling angle from varying. However, in order to correctly move them in accordance with the predetermined peeling speed, any of these conventional measuring apparatuses is compulsorily provided with a complex and large constitution.
This in turn causes much inconvenience to an operator to carry the large and heavy measuring apparatus to and from the designated location. In addition, since the operator needs to carry the substrate adhered with adhesive sheet to the apparatus-installed position for setting it to the apparatus, the operator cannot immediately measure the adhesive-strength of the adhesive sheet adhered to an optional substrate as required.